Correct Answer - Option 3 : 63.4 μW
Concept:
The power received by the receiving antenna is given by:
\({P_r} = \;{P_t}{\rm{\;}}{G_t}{G_r}{\left( {\;\frac{{\rm{\lambda\;}}}{{4\pi r}}\;} \right)^2}\)
Where:
Pt is the power transmitted from the antenna,
Gt is the Gain of the transmitting antenna,
Gr is the Gain of the receiving antenna,
λ is the wavelength of the carrier signal,
r is the distance between the transmitting and receiving antenna.
Analysis:
The numerical gain of the antenna is
Gt = 103 = 1000.
The power density in the main beam of the antenna at a distance of R = 1000 m will be:
\({{S}_{avg}}=\frac{{{P}_{t}}{{G}_{t}}}{4\pi {{R}^{2}}}=\frac{\left( 1 \right)\left( 1000 \right)}{(4\pi {{\times 1000 )}^{2}}}=63.33 ~\mu W\)
